R construct document term matrix how to match dictionaries whose values consist of white-space separated phrases
问题 When do text mining using R, after reprocessing text data, we need create a document-term matrix for further exploring. But in similar with Chinese, English also have some certain phases, such as "semantic distance", "machine learning", if you segment them into word, it have totally different meanings, I want to know how to match pre-defined dictionaries whose values consist of white-space separated terms, such as contains "semantic distance", "machine learning". if a document is "we could